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March 29, 2012 -- One in every 88 U.S. children -- and one in 54 boys -- has autism, the CDC now estimates.

The latest analysis, from a 2008 survey, shows autism is up 23% since 2006 and 78% since 2002.

"This is a large number of children and families affected by autism," study leader Marshalyn Yeargin-Allsopp, MD, chief of the CDC's developmental disabilities branch, tells WebMD.

"With nearly a doubling of prevalence since CDC started tracking in 1992, autism is officially becoming an epidemic in the U.S. We are dealing with a national emergency that is in need of a national plan," Mark Roithmayr, president of the advocacy group Autism Speaks, said at a CDC teleconference held to announce the findings.

More autism research and better services for people living with autism will be expensive. But the cost of autism already is astronomical, according to preliminary findings from an Autism Speaks-funded study by Martin Knapp, PhD, of the London School of Economics, and David Mandell, ScD, of the University of Pennsylvania.

At the new 2008 prevalence rate of one in 88 American children, autism costs the U.S. $137 billion a year. It has been estimated that 45% of Americans with autism have an intellectual disability. The lifetime cost for each person who has an intellectual disability related to autism is $2.3 million, Knapp and Mandell estimate.

Why Is Autism on the Rise?

Why the huge increase in autism? That isn't clear. A number of factors likely contribute to the increase, says Coleen A. Boyle, PhD, director of the CDC National Center on Birth Defects and Developmental Disabilities.

"We know that some of it is due to how children with autism are identified and served in their local communities," Boyle tells WebMD. "We do feel doctors are getting better at diagnosing autism. … But we don't know how much is due to better identification and diagnosis, how much is due to availability of services, and how much is a true rise in prevalence."

Roithmayr says there's a critical need to answer this question.

"The increase in prevalence is only partly explained by the broadening of the diagnosis, improved detection and more awareness," he said. "A large proportion of autism, some 50%, remains unexplained."

One hint comes from data showing that autism prevalence is higher in areas where doctors are better at diagnosing autism in kids with relatively high intellectual ability.

The CDC's huge multi-year Study to Explore Early Development (SEED), begun in 2008, is exploring various autism risk factors. The very first results should start coming out later this year. But since SEED follows kids from the time of their mother's pregnancy, it will take time for the study to mature.

It's known that autism results from a complex interaction between genetic and environmental influences. But it's not known which types of autism are most closely linked to which factors.

Autism Prevalence Varies Across States

The CDC study -- the Autism and Developmental Disabilities Monitoring (ADDM) study -- is based on data from over 337,000 8-year-olds in 14 states. That's 8.4% of all U.S. 8-year-olds. The study first used health and education records to identify kids with possible autism. Then all of the records were analyzed by autism professionals to identify kids who fit the current autism diagnosis.

Autism rates varied widely across states. Autism prevalence was one in 47 kids in Utah, but only one in 210 children in Alabama. Study sites that relied only on health records to identify kids with autism had significantly lower autism rates than sites that had both health and education records.

For example, in Colorado there was a single county with access to both education and health records. The autism rate there was twice as high as the rate in six Colorado counties with health records only.

Despite the different autism rates across sites, the overall autism prevalence detected is similar to that estimated by other national health surveys.

"This method is really the gold standard for tracking autism," Boyle says. "One thing we do know is we don't overestimate autism prevalence."

High Autism Rate a Call to Action

While it's important to understand why so many kids have autism, it's even more important to do something about it, says Rebecca Landa, PhD, director of the Center for Autism and Related Disorders at Baltimore's Kennedy Krieger Institute. Landa led one of the 14 sites in the ADDM study.

"The practical side of this is we have one in 88 children in our country with an autism spectrum disorder," Landa tells WebMD. "That has very big implications for how we prepare teachers and daycare providers -- and how to be parents."

Landa's own research shows that the earlier children with autism get proper education, the better they function -- emotionally, socially, and intellectually.

"I wish I could say things have changed a lot, but it is not enough," Landa says. "More and more universities are preparing teachers to work with kids with autism, but many times it is a single lecture or just one course. We need to be building strategies into not just special education but also in the regular education training, because the strategies we used to teach children with autism are helpful for all children.

Teaching a child does more than show that child how to act: It actually changes the way that child's brain develops.

"If we are altering children's brain, we should be thinking of education as neuro-education," Landa says. "Something as serious as altering a child's brain development will impact a child's whole live: how they interact with others, how they view themselves, how they contribute to society. These things have such huge ramifications not only for each child and each family but for our country.

Does My Child Have Autism?

There are warning signs that a child is not developing normally and may have autism. Parents should consult the CDC's developmental milestones checklist -- and those who become concerned should immediately have their child evaluated by a medical professional.